WASHINGTON -LRB- CNN -RRB- -- President Obama on Monday gathered together every confirmed member of his Cabinet for the first time as president and challenged them to cut $ 100 million in the next 90 days .

President Obama meets Monday with his Cabinet , including Defense Secretary Robert Gates , right .

Agencies will have to report how they saved on expenses at the end of the period .

The federal government has `` a confidence gap when it comes to the American people , '' Obama said at the White House .

`` We 've got to earn their trust . They 've got to feel confident that their dollars are being spent wisely . ''

The edict is part of Obama 's `` commitment to go line by line through the budget to cut spending '' and `` reform the government , '' a senior administration official said .

One potential Cabinet officer was missing from the meeting -- Kansas Gov. Kathleen Sebelius , the health and human services secretary-designate . The Senate has not voted on whether to confirm Sebelius to the post .

Obama made his savings request as the House of Representatives and Senate were returning from recess this week , ready to start reconciling their versions of the fiscal 2010 budget resolution . The president 's budget request is $ 3.67 trillion . Watch how the administration hopes to cut costs ''

In the context of the federal budget , $ 100 million in savings is a small amount , critics said .

`` Any amount of savings is obviously welcome , '' Senate Minority Leader Mitch McConnell , R-Kentucky , said . `` But -LSB- $ 100 million is -RSB- about the average amount we 'll spend every single day just covering the interest on the stimulus package that we passed earlier this year . ''

White House press secretary Robert Gibbs insisted that ordinary Americans nevertheless would appreciate the savings effort .

`` Only in Washington , D.C. , is $ 100 million not a lot of money , '' Gibbs said . `` It is where I 'm from . It is where I grew up . And I think it is for hundreds of millions of Americans . ''

The administration also contends the order signaled an important demonstration of fiscal responsibility .

`` None of these savings by themselves are going to solve our long-term fiscal problems , '' Obama said . `` But taken together , they can make a difference , and they send a signal that we are serious about how government operates . ''

The White House offered examples of how agencies already have started cost-cutting measures , including :

CNN 's Suzanne Malveaux contributed to the report .

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NEW : President Obama says , `` We 've got to earn -LSB- the public 's -RSB- trust ''

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NEW : Obama meets with Cabinet to discuss how agencies can cuts costs

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Agencies will have to report how they saved on expenses after 90 days

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Critics say $ 100 million in savings is a small amount